CSF is a water like body fluid that occupies the space between the brain and the skull and also the spaces (ventricles) inside the brain as well as in the spinal canal. It is produced in the brain to provide cushion and a homeostatic environment as well as immunological protection. CSF is produced at a rate of 0.3-0.6 ml/min and the pressure is kept at equilibrium by absorption with the same flow rate. However, when diagnosed for Hydrocephalus, there is a disturbance in the CSF circulating system that causes the ventricles of the brain to enlarge and in some cases the pressure to be increased above normal values, for instance by reduced absorption or by CSF-flow obstruction. The disturbed CSF system may lead to symptoms such as headache, unconsciousness, gait and balance disturbances and cognitive decline.
The treatment of hydrocephalus generally implies a surgical operation where a shunt system with catheters and valve is placed with an inlet in the intracranial space and an outlet in a place in the body where the fluid can be resorbed, most often the abdominal cavity (ventriculo-peritoneal, VP CSF shunt). A previously known shunt is disclosed in U.S. Pat. No. 4,861,331.
A shortcoming with the known solution is that the drainage will be dependent on the body position, e.g. if the patient is in an upright position or is lying down. Thus the drainage may be too low or too large due to changes in the body position.